A secure document such as an electronic passport, smart card or national ID card may comprise an inlay substrate or card body having one or more layers, an RFID chip or chip module, an antenna, and one or more protective layers and/or overlay layers bearing user information and/or security markings. The chip module may operate solely in a contactless mode, such as ISO 14443, or may be a dual interface module which can operate in contact and contactless mode. The chip module may harvest energy from an RF signal supplied by an external RFID reader device with which it communicates.
The inlay substrate or card body may comprise one or more layers of Polyvinyl Chloride (PVC), Polycarbonate (PC), polyethylene (PE), PET (doped PE), PET-G (derivative of PE), Teslin™, Paper or Cotton/Noil, and the like.
The chip module may be a leadframe-type chip module or an epoxy glass type chip module. Some specific examples of chip modules are disclosed herein.
The antenna conductor may be self-bonding (or self-adhering) wire comprising; a metallic core (typically, but not necessarily round in cross-section) comprising copper, aluminum, doped copper, gold, silver, or Litz wire, and may have a diameter of 0.010-0.50 mm; a first coating or “base coat” comprising modified polyurethane, and having a thickness of only a few microns; and a second coating comprising polyvinylbutyral or polyamide, and having a thickness of only a few microns.
A conventional method of mounting an antenna wire to an inlay substrate is to use a sonotrode (ultrasonic) tool which vibrates, feeds the wire out of a capillary, and embeds it into or sticks it onto the surface of the inlay substrate, in the form of a flat coil, with ends or end portions of the antenna wire connected, such as by thermo compression (TC) bonding, to terminal areas of the chip module. See U.S. Pat. No. 6,698,089 and U.S. Pat. No. 6,233,818, incorporated by reference herein.
In the manufacture of high frequency dual interface cards and contactless smart cards, an inlay containing an antenna or an inlay containing an antenna connected to an RFID chip has been required. The antenna having several turns (4-5) is routed around the perimeter of the card body to obtain optimum electrical parameters (resistance, inductance, capacitance and Q-factor). Recent developments in chip technology have permitted the reduction in the size of the antenna to accomplish a read-write distance of several centimeters.
US 2010/0176205 ('205 publication), incorporated by reference herein, discloses chip card with dual communication interface. As disclosed therein:                According to another alternative embodiment, the device for concentrating and/or amplifying electromagnetic waves consists of an antenna comprising at least one coil, disposed in the card body below the cavity intended for receiving the microelectronic module.        Advantageously, the coils of the antenna of the module are located on the periphery of the module, and the electric contacts of the terminal block are located inside the area defined by the coils of the antenna. Thus, the electromagnetic flow captured by the coils of the antenna of the module is maximum, which favourably influences the range of the contactless communication with the reader. In this embodiment, the electric contacts of the terminal block of contacts are preferably arranged in order to comply with ISO standard 7816-2.        Advantageously, the coils of the antenna of the module are located on the same side of the substrate as the microelectronic chip, and the electric contacts of the terminal block are located on the opposite face of the substrate.        
A problem with an arrangement such as disclosed in the '205 publication which incorporates the antenna into the chip module is that the overall antenna area is quite small (such as approximately 15 mm×15 mm), in contrast with a more conventional antenna which may be formed by embedding several (such as 4 or 5) turns of wire around a periphery of the of the secure document, in which case the overall antenna area may be approximately 80 mm×50 mm (nearly 20 times larger).
Canadian patent application CA 2,279,176, incorporated by reference in its entirety herein, describes a transmission module for a transponder device, transponder device and method for operating said device. The invention relates to a transmission module (14) for contactless transmission of data between a chip (15) and a reading device (12) with a coil arrangement comprising a coupling element (19 and at least one antenna coil (20) that are electrically interconnected, wherein said coupling element is used to produce inductive coupling with a transponder coil (18) which is electrically connected to the chip, and the antenna coil is used to enable connection to the reading device. The coupling element embodied as a coupling coil (19) and the antenna coil (20) are configured differently with respect to the coil parameters affecting coil impedance.
The published German application DE 4311493 describes in claim 1 a device (21, 27) used in the production of an identification unit (20) in the format of a card with a chip (24, 29) provided in a placement module for insertion into a recess (22) of a card body, whereby the placement module represents a chip carrier module (28) provided with at least one coil (25, 30) electrically connected to the chip (24, 29) in forming a transponder unit (26, 31). In claim 2, the device according to claim 1 is characterized by the chip carrier module (28) having an access side with a contact surface (39) and that the transponder unit (31) is arranged on the opposite side of the access side and is electrically connected with the contact surface (39).
U.S. Pat. No. 5,084,699 describes a coil assembly for use in an inductively powered transponder including a primary coil and a secondary coil wrapped around the same coil forming ferrite rod. The primary coil's leads are left floating while the secondary coil's leads are connected to the integrated identification circuit of the transponder. There are approximately three times as many turns to the primary coil as there are turns to the secondary coil. The primary coil is configured to self resonate at the operating frequency of the identification circuit when brought within range of an interrogator's magnetic field, thereby creating a voltage across the primary coil having a high source impedance. The secondary coil is configured to resonate at the same operating frequency, but to convert the high source impedance level of the primary coil to a low source impedance level, which is more suitable for powering the identification circuit and which substantially matches the impedance level of the secondary coil to the impedance level of the interrogator field, thereby maximizing the quantity of energy which can be transferred between the interrogator and the transponder.
U.S. Pat. No. 6,142,381 describes a chip card for contact access and contactless access to a chip arranged in a chip module, wherein the chip module is arranged in a recess (59) of a card body (49) such that outer contact surfaces (51) of the chip module are arranged at the surface (60) of the card body (49) and inner contact surfaces (53) of the chip module are connected to conductor ends (55, 56) of a coil (57) arranged in the card body to form a transponder unit, where the coil has the form of a wire coil (57) and the depth (t) of the recess (59) which accommodates the chip module is such that wire ends (55, 56) arranged in the region of the recess (59) have a contact flattening (63) formed by the machining process for the formation of the recess (59).
U.S. Pat. No. 6,310,778 describes an IC card module (20) for producing an IC card (118) having at least one coil (46) and at least one chip (23) for the formation of a transponder unit, with the chip and the coil being connected together by way of a module carrier (21) which renders possible not only an electrically conductive connection between the chip and the coil, but also an electrically conductive connection with an external contact face (38) of the module carrier and the chip, wherein the IC card module (20) has a retaining device (41) which is at a distance from the external contact face (38) by an offset R and projects laterally beyond the external contact face, and also a method for producing an IC card with use of such an IC card module.
U.S. Pat. No. 6,406,935 describes a hybrid-contact contactless smart card manufacturing process and specifically a manufacturing process for hybrid-contact contactless smart card in which the antenna is on a fibrous material such as paper. This process includes a manufacturing step to screen print the antenna onto the support, a step to laminate the card body onto the antenna support by hot press molding, a step to mill a cavity in the card body opposite the side of the support bearing the screen print for housing a module comprised of a chip and a double-sided circuit and a step for inserting the module in the card. Cutouts made in the corners of the antenna support prior to the lamination step enable the card bodies to be bonded together. The card thus obtained allows a posteriori viewing of any mechanical misuse to which it may have been subjected (extreme bending).
U.S. Pat. No. 6,719,206 describes a data transaction card having an interface for bi-directional contactless communication, and comprising a support (20) having a cavity (12) for accommodating therein a chip carrier therein module (10). The chip carrier module comprises a substrate (11) having a first side (45) and a second side (46), and an integrated circuit (30) mounted on the first side of the substrate for managing functions of the data transaction card. A coil antenna (40) is electrically connected to the integrated circuit for inductive coupling with remote antenna, connections to the coil antenna being accessible from the first side of the substrate. The chip carrier module is packaged into one discrete unit so as to be amenable to mechanical assembly of the data transaction card without requiring additional electrical connections between the support and the chip carrier module during or subsequent to assembly. Such a construction allows for efficient mass-production of the data transaction card.
US 2009/0057414 describes a method of manufacturing a microelectronic device with contactless operation, mainly for electronic passports. An antenna is made on a thin, flexible substrate. A perforated sheet that is thin and calibrated, and that has at least one cavity in its thickness, is placed on the substrate. A microelectronic chip is placed in each cavity of the perforated sheet and the output contacts of the microelectronic chip are connected to corresponding terminals of the antenna. The microelectronic chip is protected by sealing off the cavity that contains the chip. The method is particularly adapted for manufacturing electronic radio frequency identification devices, in particular for electronic passports.
US 2010/0176205, mentioned above, describes a chip card with a dual contact and contactless communication interface, including a microelectronic module (11) and a card body (22) provided with a cavity (23) which can receive the microelectronic module, said microelectronic module (11) being formed by a substrate (15), the first face thereof bearing a terminal block of electric contacts (4) and a second face thereof bearing a first microelectronic chip (9) electrically connected to the terminal block of electric contacts (4) and a second chip (10) electrically connected to the terminals of an antenna (13), the coils of which are disposed on the second face of the substrate of the electronic module. The invention is characterised in that the card body (22) includes a device (18) for concentrating and/or amplifying electromagnetic waves, which can channel the electromagnetic flow received, in particular, from a contactless chip card reader toward the coils of the antenna (13) of the microelectronic module (11).
US 2010/0283690 describes a secured document in the form of a booklet of at least one sheet which may be folded about a folding axis, the document having a transponder with an electronic chip provided with a memory for storing data and a transponder antenna. The document also includes a foldable amplifier antenna, distinct from the transponder antenna and arranged on the document such that, when the same is open, the amplifier antenna amplifies the electromagnetic flux received by the transponder antenna to permit communication of the document with a remote reader and, in the closed position of the document, the amplifier antenna reduces the electromagnetic flux received by the transponder antenna beneath a minimum threshold permitting communication of the electronic chip with a remote reader.
US 2011/0163167 describes a contactless smart card that comprises a card body and an electronic module provided with an electronic chip connected to the terminals of an antenna, the electronic module being arranged in a recess formed in the card body, wherein the exposed surface of the electronic module comprises at least one graphic security element capable of protecting said electronic module and the contactless card against attempts at fraud.